Bathroom tips and ideas

Copper pipe expands when hot, which could cause problems if embedded in hard materials like cement/plaster. I use Densotape to wrap it in because it provides corrosion protection as well - it is unfortunately very messy to work with.
Unless you are very confident in your DIY skills, I would recommend professional help with hidden pipework, because all measurements need to be precise and position of pipes well planned. It can be very frustrating if after the tiles are installed you find out that your tap or radiator doesn't fit, is in the wrong position or if you need to put a fixing exactly where your pipe is.
It is easy to get confused about position of pipes after the tiles are installed, and no detector will show where your waste pipe is - make pictures, measurements, notes and remember to make use of them before you start drilling.

Steel baths are preferable when a shower is to be installed above the bath - they are more rigid and easier to fix properly. Acrylic baths are not cold to touch, generally cheaper and strong enough for standard use.

If you have low water pressure, it might be better to use British made brassware. Foreign imports are often suited for higher pressure. That is if you don't want to install a pump or replace your boiler - modern combi boilers generally provide good pressure.

My experience with epoxy grout is very positive. It is the only truly waterproof grout and is commonly used in areas where a higher level of hygene is required - it is not porous and is therefore easy to clean. I like to use it in wet floor rooms on top of whatever damp proof barrier I have used for the floor. This way you get extra peace of mind regarding leaks, and an easier to clean floor.
Epoxy grout is unfortunately a lot messier to work with, compared to the common cement based grouts. It might not be suitable for certain types of tiles - try on a small area first, or on a spare tile, and do read the text on the tub. Most importantly, I always use cloths, and lots of them, to clean up - rather than a grouting sponge.

See the section on planning for waterproofing materials.